Question

Candidates of four schools appear in a mathematics test. The data were as follows:

Schools	No. of Candidates	Average Score
I II III IV	60 48 Not available 40	75 80 55 50

If the average score of the candidates of all the four schools is 66, find the number of candidates that appeared from school III.

Answer 1

Let the number of candidates appeared from school III is.

Then the given data can be tabulated as

The row of x denotes the average scores and the row of f denotes the number of candidates. We have to find the value of p using the information that the average score of all the four schools is 66.

Prepare the following frequency table of which the first column consists of the average scores and the second column the number of candidate (frequencies). Multiply the frequency of each row with the corresponding average scores to obtain the third column containing.

Find the sum of all entries in the second and third column to obtain N and respectively. Therefore,

The mean is

Hence, we have

Hence the number of candidates appeared from school III is.